1. Field of the Invention
This invention relates to the problem of global temperature rise resulting from heat being trapped within the atmosphere by certain gases and vapors occurring naturally as well as by man-made pollutants, e.g., the so-called greenhouse effect. More specifically, the invention relates to an apparatus and method for radiating a greater amount of thermal energy from the earth into space then would naturally occur, thus providing localized cooling and possible climate control.
2. Description of the Prior Art
In the opinion of a majority of scientists in this country and around the world, the earth is experiencing a global atmospheric warming due to the ever increasing concentrations of certain naturally occurring gases and manmade pollutants in the atmosphere. Since the industrial revolution, the accelerated burning of fossil fuels in the industrialized nations has resulted in the release of a number of radiation absorbing pollutants into the atmosphere, among them methane (CH.sub.4), carbon dioxide (CO.sub.2), nitric oxide (NO), and sulphur dioxide (SO.sub.2). In addition, a number of radiation absorbing man-made pollutants have been released into the atmosphere during the past century. A broad range of chlorinated fluorocarbons (CFC's) are involved, principally the family of Freon gases.
When solar radiation is intercepted by the earth, a certain amount of incoming radiation is absorbed by the atmosphere. FIG. 1 depicts the variation of solar intensity versus wave length for radiation outside the earth's atmosphere and for a typical spectrum at the surface of the earth. Curve 10 represents solar intensity outside the atmosphere, while curve 12 depicts the same at the surface of the earth. A comparison of curves 10, 12 will demonstrate that a substantial amount of radiation absorption occurs within the earth's atmosphere. On a global basis, the amount of solar radiation incident on the earth's atmosphere is about twice the amount that reaches the earth's surface A few naturally occurring instances of absorption include a region 14 between the 0.8-1.0 .mu.m range, which is attributable to oxygen and water vapor, a region 16 in the 1.0-1.2 .mu.m range and attributable to water vapor, and a third region 18 in the 1.3-1.5 .mu.m range, which is attributable to water vapor and carbon dioxide.
As may be seen in FIG. 1, the sun transmits energy to earth at wave lengths principally in the 0.3-1.0 micrometer region. The radiation which reaches the surface of the earth provides energy for life processes, then ends up as relatively low temperature heat in the environment. The average amount of heat received from the sun on an annual basis must be reradiated to space, or the temperature of the earth will increase. However, once the relatively short wavelength solar energy is absorbed by the environment (air, land and water), it resides at environmental temperatures, and this changes the wavelengths at which it will be reradiated.
FIG. 2 is a representation of spectral radiance versus wavelength, plotted on logarithmic scales, for black body radiators at a number of different temperatures ranging from 200.degree. K. to 6,000.degree. K. Superimposed upon the curves in FIG. 2 are bands depicting the characteristic ranges of absorption for the various gases and pollutants discussed above. Curve 20 in FIG. 2 depicts black body radiation at a temperature of 273.degree. K. (32.degree. F.), which is adequately close to a representation of the average temperature of the earth on an annual basis. As may be seen from curve 20, the environment has radiation frequencies which are centered in the mid infra-red. Herein lies the cause of the greenhouse effect, because the absorption bands for gases such as carbon dioxide, methane and others lie in the same region. Less than 10% of the solar radiation that reaches the earth's surface can be directly reradiated to space through the transmission bands shown on FIG. 3. The balance is part of a complex and continuous exchange of heat between the earth's surface and it's atmosphere, which is characterized by a net outflow of heat by indirect radiation to space.
Various solutions have been proposed for solving the problem of global warming due to the greenhouse effect on a global basis, but their feasibility on either an economic or political basis is questionable. For example, the amount of carbon dioxide released into the atmosphere could be sharply reduced by adoption of a proposal to stop the burning of fossil fuels such as oil and coal. The difficulty with this is that the world is heavily dependent on fossil fuels, and any sudden changes in energy consumption patterns would seriously disrupt the economies of virtually every nation. A second proposal has called for the deployment of satellites in space having large reflective surfaces to serve as artificial clouds. Besides the rather significant cost of such an approach, it would block out sunlight and have the effect of reducing the evaporation of water, which is necessary to produce rain. It has also been suggested that satellites be deployed having fields of cells for converting solar energy to electricity, and that energy so produced be transmitted to earth's surface via microwave radiation. Disadvantages of this approach are the significant cost of the equipment involved, and the probable logistic difficulties and ecological harm that would result from the transmission of large amounts of microwave energy through the atmosphere.
One common element of all of the proposed solutions mentioned above is the global nature of the undertaking involved, implicit in which are serious economic and political impediments to immediate implementation. It is clear that there has existed a long and unfilled need in the prior art for an apparatus and method for providing localized climate control which operates by increasing the amount of heat that is directly radiated to space from the earth's surface, provides a built-in economic incentive to produce and utilize, is relatively inexpensive, is harmless to the environment, and is expandable from localized to global proportions.